Discover the world’s largest factory in Australia

The world’s largest living plant has been identified in shallow waters off the coast of Western Australia, according to scientists. Shown here is an underwater image of seaweed in Shark Bay in Western Australia. (Rachel Austin)

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The world’s largest living plant has been identified in the shallow waters off the coast of Western Australia, according to scientists.

The sprawling seaweed, a flowering marine plant known as Posidonia australis, stretches more than 112 miles in Shark Bay, a wilderness protected as a World Heritage site, said Elizabeth Sinclair, a research associate in the School of Biological Sciences and the Oceanic Institute. at the University of Western Australia.

That’s about the distance between San Diego and Los Angeles.

The plant is so large that it reproduces itself, creating genetically identical branches. This process is a method of reproduction that is rare in the animal kingdom although it does occur in certain environmental conditions and occurs more often among certain plants, fungi and bacteria.

said Sinclair, author of a study on seaweed published late Tuesday in the journal Proceedings of the Royal Society B.

“The answer definitely surprised us – just one! That’s it, just one plant has expanded over 180 kilometers into Shark Bay, making it the largest known plant on Earth,” she said by email.

Sinclair and her colleagues sampled 10 sites across the Shark Bay seagrass meadow range in 2012 and 2019. The research team also measured environmental conditions including depth, water temperature and salinity.

“We’ve been studying cold-water seaweeds in South Australia for a while, to understand how much genetic diversity they are and how closely related the meadows are,” Sinclair said.

Scientists were able to sequence DNA from seaweed samples, revealing that it was a single plant.

“The plant was able to continue to grow through vegetative growth – extending its roots (root stems) outward – the way a buffalo grass could be in your back garden, extending outwards. The only difference is that the seaweed roots lie beneath the sandy sea floor. , so you don’t see them, just sprouts inside the water column.”


What’s even more interesting is that it has twice as many chromosomes as the other populations we’ve been studying. She has 40, not the usual 20.

Elizabeth Sinclair, School of Biological Sciences and Oceanographic Institute


“The most interesting thing is that it has twice the number of chromosomes than other groups we’ve been studying. It has 40 chromosomes, not the usual 20,” she added.

Seaweeds live in seacoasts and estuaries worldwide.

The study suggested that reproduction by cloning helped the seagrass meadow adapt to habitat conditions that were more extreme than where seagrass is normally found — saltier waters, higher levels of light and wide fluctuations in temperature.

Sinclair said the seagrass meadow covered roughly 77 square miles, or 49,000 acres — bigger than Brooklyn. That’s a much larger area than Pando rocks the aspen trees in Utah, often described as the largest plant in the world. The clone is spread over 106 acres, and consists of more than 40,000 individual trees, according to the USDA Forest Service.

The researchers said that the seagrass of Shark Bay is about 4,500 years old, but it is ancient, but its age does not break records. The Posidonia oceanica plant discovered in the western Mediterranean extending up to 9.3 miles may be older than 100,000 years.

“Seaweed clones may persist almost indefinitely if left undisturbed, because they depend on horizontal rhizome expansion, rather than sexual reproduction,” Sinclair said.

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